Stilbene monotriazole brightening agents



United States Patent ()fiice Patented, July 25, 1961 This inventionrelates to novel silbenenaphthotn'azole compounds possessing new anduseful properties which render them particularly useful as fluorescingoptical bleaching or whitening agents.

It is well known that textiles tend to develop a yellowish shade onaging which cannot be removed by ordinary methods of bleaching orwashing. The heretofore used methods of hitting white materials withflue pigments or fugitive blue dyestulfs have become quite obsolete inmodern laundry practice and have been largely superseded by methodsemploying fluorescent optical bleaching agents or brighteners asadditives to the soap or detergent in the washing bath. Thesebrightening agents are usually conveniently supplied commercially in theform of intimate admixtures with the soap or detergent in bars, flakes,powders, etc. The fluorescent optical bleaching agents perform theirdesired function by virtue of their characteristic absonption ofultra-radiations and subsequent conversion of this energy to lightenergy within the visible spectrum. This converted and emitted lightenergy tends to neutralize any yellowness of the material and therebyincrease the apparent whiteness thereof.

Compounds which have been suggested and employed as fluorescentbrightening agents include the following:

(I) Acylated derivatives of 4,4'-diaminostilbene-2,2'- disulfonic acid.

(II) Acylated derivatives of 4,4'-diamino-diphenyl-2,2'- disulfonicacid.

(III) Triazyl derivatives of diamino stilbene disulfonic acid.

(IV) Triazyl derivatives of diamino diphenyl disulfonic acid.

(V) Acylated derivatives of diamino dibenzothiophene dioxide, etc.

Compounds of the Types I and II are disclosed in U.S. Patents 2,518,059and 2,643,198 and in British Patent 584,484.

Compounds of the Types III and IV are disclosed in U.S. Patent 2,618,636and in application Serial No. 381,- 856 published May 11, 1954 by theA.P.C.

Compounds of Type V are exemplified in U.S. Patents 2,563,493 and2,563,795.

In addition to the five types mentioned above, other triazyl compoundshave been suggested. Thus U.S. Patent 2,713,054 discloses monotriazolesof the type CHsO 2 U.S. Patent 2,713,055 discloses monotriazoles of thetype F 1 H2C I -i NaOaS L N/ J N: SOQNB 8H U.S. Patent 2,713,056discloses monotriazoles of the type N YC2/ 6 N N H N 1 wherein Xdesignates oxygen, sulfa, or imino, and Y alkyl or aryl.

U.S. Patent 2,713,057 discloses monotriazoles contain ing a silbenemoiety of the type formulated in claim 2:

CHaO

None of the aforementioned patents relates to stilbene monotriazolescontaining a naphtho substituent. Such compounds, however, are disclosedin Patent 2,784,183, and representative of the compounds in the latterpatent is the following compound:

N S 03H The compounds of the present invention are naphtho monotriazolestilbenes containing a single sulfo substitneat and characterized by oneof the following two formulas:

Q QF

and (A) The novel compounds of this invention are characterized byhaving excellent fiber substantivity, an aesthetically more desirablehue as contrasted with an aesthetically undesirable yellow hue of someof the prior art brightening agents, a greater apparent whiteness thanprior art compounds, outstanding resistance to bleaching agents commonlyused in laundering processes, an excellent lightfastness. As a result ofthese remarkable properties fabric washed with soaps or other detergentscontaining small amounts of the novel compounds of this inventionusually in the form of the sodium or other alkali metal salt become muchbrighter in the case of colors and whiter for others than fabrics whichare washed either in the absence of such brightening agents or in thepresence of the previously known brightening agents.

The compounds of this invention may also be incorporated in syntheticfibers and fabrics particularly during the manufacture thereof andespecially in those of cellulose, cellulose acetate and the like, byadding a small amount of the brightening agent to the spinning solutionsor precipitating baths in order to achieve a noticeable increase in thewhiteness of the finished product. These brighteners may also be used toeffect a whitening of paper by the impregnation thereof (with theselected brightening agent) or by the inconporation of the brighteningagent in the paper making pulp prior to the final drying thereof.Additionally, the brightening agents of this invention may be employedto effect a whitening of waxes, gums and the like by a ding smallamounts of the agent to such substances.

The two compounds of this invention, as will be noted from the aboveformulas, have only a single sulfo substituent in the entire molecule.In Formula A this sulfo substituent is present in the stilbene moietymeta with respect to the ethylene bridge, and in the case of Formula Bthe sulfo is present in the -position of the naphtho ring. In compound Bit will further be noted that the stilbene moiety is devoid of anysubstituents. It is completely unexpected that either one ofthese twocompounds would be outstanding brighteners in the light of prior artstatements and knowledge to the effect that in structures of the typeherein contemplated, the stilbyl radical should contain a substituent inone of the ortho or para positions, and that compounds of this typeunsubstituted in the stilbyl radical are of no technical use asbrightening agents. Notwithstanding this teaching and knowledge in theprior art, applicants have discovered that the two compounds of thisinvention are not only outstanding and superior brightening agents, andin particular on cotton and nylon but that they are actually farsuperior in fluorescence and in lack of self color than the compoundswhich have heretofore been considered outstanding in the prior art.

It is therefore an object of the present invention to provide new anduseful compounds having outstanding utility as brightening agents...

It is another object of this invention to provide new and useful naphthomonotriazole stilbene compounds which are outstanding brighteningagents.

It is another object of this invention to provide new and usefulcompounds which are outstanding, optical bleaching or whitening agents,and which are characterized as naphtho monotriazole stilbenes.

It is still another object of this invention to provide methods foreffecting the brightening or whitening of organic materials and inparticular, textile materials.

It is a still further objectof this invention to provide improvedbrightening organic materials and in particular, textile materials.

It is a still further object of this invention to provide an improvedbrightening organic material, and in particular, textile materials, byincorporating therewith new and novel naphtho monotriazole stilbenecompounds of the type hereinafter to he described.

The compounds of this invention are prepared in the general manner ofthe prior art by coupling a diazotized stilbene to the selectednaphtylamine and thereafter oxidizing the resultant azo amino compoundto the corresponding triazole form. The oxidation to the latter formresults in the conversion of an ortho positioned, primary amino group(ortho to the azo linkage) to the hetero atoms of the triazolyl ring.The procedure for this oxidation may vary depending upon the choice ofthe oxidizing agent. For example, when one uses ammoniacal (or otherorganic base, e.g., pyridine, etc.) copper sulfate as the oxidizingagent, the resultant byproducts of such reagent may be removed byadjustment of the pH of the solution, i.e., the reduction products ofthe oxidizing agents may be solubilized by making the solution moreacidic, so that the by-products are removed in the filtrate by afiltration step. Alternatively, the by-products may be removed in thefiltrate by making the reaction medium alkaline with ammonia (pH 11)prior to filtration. While it is preferred to use metallic (icous)oxidizing agents such as copper sulfate, ferric chloride, ferric NH SOetc., one may also employ hydrogen peroxide, KMnO K Cr O CaOCl, Naperborate, oxygen, etc.

The following examples will serve to illustate the present inventionwithout being deemed limitative thereof.

EXAMPLE 1 (A) Preparation of Into a 500 ml. flask fitted with stirrer,thermometer and condenser is charged 24.1 gms. (0.125 mole) of thesodium salt of 4-sulfamyltoluene and 75 mls. triethanolamine. Thematerial is stirred to a smooth slurry, after which 26.5 gms. (0.25mole) benzaldehyde and 34.3 gms. (0.25 mole) 4 nitrotoluene are added.The mixture is heated to C. and stirred 40 hours at this temperature.After this period 200 mls. of glacial acetic acid is added, the materialis cooled to 20 C. and stirred until no further precipitation occurs.The light yellow precipitate is filtered and the presscake is carefullywashed with 50 mls. glacial acetic acid. The filter cake is reslurriedin 350 mls. water, and 10' mls. of 40% sodium hydroxide is added toraise the pH to about 12.5. The slurry is refiltered, washed with 2.50mls. water and finally with 50 mls. glacial acetic acid. The product isair dried at 80 C. to give 4-nitrostil bene.

(B) Reduction of 4-nitr0stilbene to 4-amin0stilbene Into'a l-literbeaker fitted with stirrer and thermometer and heated with a gas burneris charged 200 mls. water, 35 gms. iron borings, and 4 mls. ofconcentrated hydrochloric acid. The slurry is heated to 95 C. andstirred 10 minutes at 95 C. At 95l00 C. over a period of hour there isadded a preheated C.) solution of 21 gms. of the above 4-nitrostilbenein 100 mls. of'dimethyl formamide. The charge is then stirred for 1 hourat 95 C. 9.0 gms. of sodium carbonate is then added, increasing the pHto 10. The slurry is filtered at 90 C. through a Celite bed. The ironcake is washed with 300 mls. of dimethyl formamide heated to 95 C. Thefiltrate and washings are combined and diluted to 3 liters volume withWater. The precipitate is filtered, reslurried with 500 mls. water and50 mls. of concentrated hydrochloric acid, to yield a mass of pH'=l. Thematerial is evaporated to dryness giving 4-amin0stilbene hydrochloride.

(C) Diazotization of 4-aminostilbene hydrochloride and coupling toZ-naphthylamine-S-sulfonic acid A mixture of 5.04 grnb. (.018 mole) of4-aminostilbene hydrochloride, 100 mls. of glacial acetic acid, and 25mls. of water is heated to effect solution, followed by addition of 9.0mls. of concentrated hydrochloric acid. The slurry is stirred and cooledto 8 C. At 812 C. 15.5 mls. of 10% sodium nitrate is added. The diazo isstirred /2 hour at 10 C. 4.5 mls. of 10% sulfarnic acid is added todestroy excess nitrous acid. 5.4 gms. (.024 mole) of2-naphthylamine-S-sulfonic acid is dissolved by heating at 90 C. in 75mls. water and 10 mls. of 30% sodium carbonate. This solution is addedto the diazonium solution. After stirring /2 hour, a dropwise additionof 75 mls. of 20% sodium acetate is made over a period of 1 hour. Theslurry is stirred for 18 hours, after which time tests for diazo anddiazoamino are negative. The slurry is filtered and washed with water togive the product:

(D) Oxidation of the above product to the brightener N SOaNa A mixtureof 29.5 gms. of the above dye cake, 120 mls. of picoline, and 25 mls. ofwater is added to a 500 ml. flask equipped with stirrer, theremometer,reflux condtnser andheating mantle. The material is heated to 95 C.giving a complete solution. A 90 C. solution of 13 gms. of-coppersulfate +5H O in 30 mls. water is added. The charge is stirred /z hourat reflux, after which 24 mls. of 25% sodium sulfide +2.5H O is added toneutralize the copper salts. The slurry is filtered through a Celite bedat 90 C. The copper sulfide cake is washed carefully on the funnel with100 mls. of picoline preheated to 90 C. The Wash and mother liquors arecombined in a 1 liter flask equipped for steam distillation and 10 mls.of 20% sodium carbonate solution is added. The charge is distilled withsteam, removing the picoline. The brightener precipitates upon coolingto 70 C. and is filtered and washed with water. The presscakeis airdried to give the brightener:

N S03Na 6 EXAMPLE 2 Application of the above brightener to cotton H H OO some in 1 liter of water by heating to C. A 50 ml. aliquot of thismaterial is then diluted to 250 mls., giving solution (A). The cottoncloth is agitated in the launderometer jar for 30 minutes at F. Afterthis time the cloth is removed, rinsed, and dried. Using a fluorescentphotometer a brightness reading of 75 is obtained on the dyed cloth.

EXAMPLE 3 A similar 5 gm. swatch of Indianhead cotton is dyed in similarmanner with equal weight of a brightener of the formula and gives abrightness of 70.

EXAMPLE 4 The two brighteners of Examples 2 and 3 are applied to 5 gm.swatches of nylon in the same fashion. A brightness reading of 22 isobtained on nylon for the brightener of formula:

N SOsNa and a brightness reading of 20 was obtained from the thebrightener (A) Preparation of SONa A mixture of 34.3 gms. (0.25 mole) of4-nitrotoluenc, 50 mls. of carbowax 400 (polyethyleneoxide) is heated to80C. There is added 19.3 gms. (0.10 mole)'of the sodium salt of4-sulfamyltoluene (prepared by treating 1 mole of 4-sulfamyl-toluenewith 1 mole ofsodium hydroxide in water and evaporating to dryness).Over a period of 19 hours 26 gms. of 3-forrnylbenzene sulfonic acid,sodium salt (100%) is added, adding, 1.3 gms. of the latter every hour.The charge is then diluted with 1 liter of water and 25 mls. of 40%sodium hydroxide. The slurry is heated to the boil and the waterinsoluble material is filtered oil. The press cake is washed with 250mls. of hot water. The water layer is extracted with 1 liter of toluene,removing excess 4 nitrotoluene. To the water layer is added 125 gms.sodium chloride. It is cooled to 5 C., filtered and washed with 50 mls.of 20% saltsolution to give SOSNa (B) Reduction of SOrNa to the amine Aslurry of 120 gms. of iron borings in 800 mls. of hot water is etchedwith 12 mls. of concentrated hydrochloric acid by heating minutes at 95C. Maintaining constant volume and keeping temperature at 95 -100 C.there is gradually added 56 gms. (0.174 mole) SO Na After all is added,the slurry is stirredfor 1 hourat 95 -100 C. The material is madealkaline to phenolphthalein by adding 10 gms. of sodium carbonate. It isfiltered at 95 C. through a Celite bed and the iron cake is wased with 1liter of boiling water. The filtrate is treated with 95 mls. of 50%sulfuric acid. The precipitated material is cooled to 15% C., filteredand washed with 250 mls. water to give on air drying the compound (C)Diazotization of SOQH and coupling to Z-naphthylamine 8.0 gms. (0.028mole) of by addition of 1.0 ml. of 10% sulfamic acid. There is thenadded a solution of 4.6 gms. (0.0318 mole) of Z naphthyIamine in 15 mls.of glacial acetic acid. After 2 hours additions of 150 mls. of glacialacetic acid and 7.0 gms. of sodium acetate are made to the slurry. Thedye is stirred overnight to complete the coupling. The material iscooled to 10 C., filtered and washed with 50 mls. water to give apresscake of the dye (D) Oxidation of the above dye to the brightener:

SOaNa N Into a 500 ml. flask fitted with a stirrer, thermometer, refluxcondenser and heating mantle are charged the above dye presscake and 200mls. picoline. The material is heated to C. and there is added asolution of 20 gms. of copper sulfate +5H O in 50 mls. water. Thematerial is stirred at rcflux'for 20 minutes, then the copper sulfate isprecipitated with 50 mls. of 20% sodium sulfide +2.5H O. The material isfiltered hot through Super Cel and Washed with 250 mls. of hot picoline.The filtrate and wash liquor are combined and steam distilled. Theproduct is cooled to 16 C., filtered and washed with 75 mls. cold Water.The presscake is vacuum dried at C. to give the brightener:

EXAMPLE 6 Application to cotton and nylon of the following brightener:

S O 3N8 N gives brightness readings about 25% lower than those obtainedwith the brightener used in Example 6.

Application to cotton at 2% concentration of the weight of the fabric,of a prior art brightener of the formula:

gives an undesirable yellow hue, whereas our brightener of the formula:

S OaNa remains white on the cotton applied at this concentration. Thisditference is due to the fundamentally greater self color of thebrightener of the prior art which can be determined most accurately byan examination of the ultra-violet absorption curves of the twomaterials:

Thus a comparison of the absorption curves shows that there is overtwice as much self color in the prior art compound as in the compound ofthis invention of Formula II. Thus K=2.2 at 400 mg for (I), whereasK=0.5 at 400 m for (H).

EXAMPLE 7 The monotriazoles of this invention (that is, of Example 1 andExample 5) are further tested for chlorine stability in the followingmanner. 100 parts of a Water solution containing 0.00032 part of thebrightener, 25 parts Clorox solution (15 parts Clorox containing 0.052g. active chlorine per ml. in 1000 parts of water), and 0.4 part Supersuare heated to 130 C. After 5 minutes, suificient sodium-m-bisulfitesolution (2.5 g. sodium-m-bisulfite per liter of solution) is added todestroy the Clorox and 5 parts of cotton fabric added. The solution withthe fabric is then placed in a launderometer for 20 minutes at 130 F.The cotton swatch, after rinsing twice in warm tap water and air dryingat 55 C., is then measured for brightness with a fluorescent photometer.Employing the compound of Example 1, the reading is 80. The compound ofExample 5 gives a reading of 92.

10 EXAMPLE 8 wherein one X is hydrogen and the other is M, wherein M isselected from the group consisting of hydrogen and alkali metals.

2. The compound of the formula:

S OaNa 3. The compound of the formula:

References Cited in the file of this patent UNITED STATES PATENTS2,784,183 Keller et al. Mar. 5, 1957 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent No, 2393,5592 July 25 1961 Albert F.Strobel et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Ratent, should read as"corrected below.

Column l line 11 for silbenenaphthotriazole" readstilbenenaphthotriazole line 41 for the patent number "2 5l8 O59 read2,58%059 --3 column 7 q line 49 for "15% Cu" read 15 C.

Signed and sealed this 26th day of December 1961.

( SEAL) Attest:

ERNEST W. sWIDEE DAVID L. LADD Attesting Officer Commissioner of PatentATENT OFFICE ERECTION July 25 1961 UNITED STATES P CERTIFICATE OF COPatent No 2993 892 Strobel et alo fied that error appears in the aboverreotion and that the said Letters Batent. shoul Albert F.

numbered pao d read as It is hereby oerti ent requiring oo correctedbelow.

" read ent number for thotriazole for the pat,

line 4 q "silbenenaph line 47 column line 11 for hthooriazole d 2 58lO59 ----'g,

Column 1. stilbenenap 2 5l8 O59 rea "15% (1.," rea Signed and sealedthis 26 (SEAL) Atteet:

' DAVID L. LADD ERNEST W. SWIDER I Commissioner of Patent AttestingOfficer U SCOM M-D

1. THE COMPOUND OF THE FORMULA: